Bly Barn reflects the success of Orleans County dairying in the first decade of the twentieth century and is a landmark example of the last generation of northern New England dairy bank barns. After building this 50 × 180–foot barn in 1904, Harley H. Bly dramatically expanded the twenty-cow dairy to more than one hundred on the farm his father, Edward Bly, left him. The barn's northern gambrel end extends to cover the bridge into the haymow, also creating storage rooms on either side of the bridge. The barn's original double-boarded stable floor was entered beneath the bridge and the manure basement was exposed on its south and west ends. Still in place is a trussed open double-bay at one end of the interior hay drive, which allowed hay wagons to turn around rather than back out. The basement has been converted to a ground-stable design and an ell added on the west side. By 1910 new dairy barns in Orleans County abandoned the northern New England manure-basement design, popular since the 1840s, in favor of washable concrete floors and ground-level stables, but almost all would also adopt the greater haymow capacity of the gambrel roof and many would keep the labor-saving covered bridge into the haymow.